Field of the Invention
The present invention relates to a laminate structure and a manufacturing method thereof.
Description of the Related Art
A cylindrical indium target is typically manufactured by casting indium with a backing tube.
Various conventional methods for casting a target have been developed. For example, an apparatus for continuous casting of a hollow billet is disclosed in Japanese Patent Laid-Open No. 61-135452 as follows. A core is disposed in a hollow part with open upper and lower ends of a hollow water-cooled casting mold having a cylindrical or other cross section. A molten metal is continuously supplied into an annular casting path formed between the water-cooled casting mold and the core. Meanwhile, a pedestal disposed at first to seal the lower end of the casting path is lowered, such that an annular ingot is continuously pulled out to manufacture a hollow billet, with the solidification starting point at which the supplied molten metal is solidified in the casting path being maintained at approximately constant. The core includes: an insulation member (a) formed of insulating material having a molten metal receiving tank for temporarily receiving a molten metal to be supplied into the casting path and at least one molten metal guiding part for guiding the molten metal from the molten metal receiving tank into the casting path, which is integrally formed in the upper part; and a casting member (b) formed of graphite or carbonaceous material to form a core-side casting surface tapering downward with a smaller diameter in a downward direction in a proper vertical length range including the expected solidification starting point on the core-side, which is fixed to the insulation member.
Further, a casting method of a hollow billet is disclosed in Japanese Patent Publication No. 1-31971 as follows. In the hot top casting method, a molten metal is supplied to a casting mold from a casting furnace to a molten metal receiving tank made of insulating refractory for holding the molten metal above the casting mold through a launder (trough). A hollow billet is continuously cast with a water-cooled casting mold in which a core made of refractory is concentrically disposed. A coolant flow pipe for circulating a coolant inside the core and the temperature detecting end of a temperature detector are disposed inside the core. Corresponding to the temperature detected by the temperature detector, the flow rate or the temperature of the coolant inside the coolant flow pipe is adjusted, so that the temperature of the core is controlled.
A cylindrical indium target is made by casting molten indium into a casting mold having a backing tube inside thereof. The oxide slag contained in the molten indium is floated on the molten indium because of a lower density than indium. Accordingly, the slag rarely remains in indium. The slag often adheres to the backing tube and remains in indium in many cases. When the molten indium is cooled and solidified while the slag remainings, the oxide slag adhered to the backing tube is solidified as it is, which may cause an adhesive failure. The occurrence of the adhesive failure causes a cooling failure during sputtering, resulting in abnormal discharge and the like.
The object of the present invention is therefore to provide a laminate structure having an indium target with the occurrence of defects being well controlled and excellent in the adhesion between the indium target and the backing tube.